Linked by Thom Holwerda on Sun 16th Mar 2008 21:51 UTC, submitted by Oliver
"In May 2007 I ran some benchmarks of Dragonfly 1.8 to evaluate progress of its SMP implementation, which was the original focus of the project when it launched in 2003 and is still widely believed to be an area in which they had made concrete progress. This was part of a larger cross-OS multiprocessor performance evaluation comparing improvements in FreeBSD to Linux, NetBSD and other operating systems. The 2007 results showed essentially no performance increase from multiple processors on dragonfly 1.8, in contrast to the performance of FreeBSD 7.0 which scaled to 8 CPUs on the benchmark. Recently Dragonfly 1.12 was released, and the question was raised on the dragonfly-users mailing list of how well the OS performs after a further year of development. I performed several benchmarks to study this question."
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RE[3]: Makes sense.
by PlatformAgnostic on Mon 17th Mar 2008 05:35
in reply to "RE[2]: Makes sense."
Member since:2006-01-02
I did it for you 
.
Writing a fine grained kernel is hard, especially when you need to support some functionality that's not so friendly for large MP systems.
Maybe Dillon's approach is right. Instead of trying to coordinate actions between processors in a lock free or finely grained manner while trying to maintain tons of shared state, why not treat your large MP machine as many smaller ones that are coordinated at a higher level?
The Google cluster is a great example of this. They don't really need a scalable OS at all: a simple kernel that efficiently manages I/O and gets out of the way of the one executing task on a particular node is all that's needed. Everything else is coordinated from their aggregation servers and their distributed namespace/locking system.
Member since:2006-04-17
I did it for you .
Writing a fine grained kernel is hard, especially when you need to support some functionality that's not so friendly for large MP systems.
Maybe Dillon's approach is right. Instead of trying to coordinate actions between processors in a lock free or finely grained manner while trying to maintain tons of shared state, why not treat your large MP machine as many smaller ones that are coordinated at a higher level?
. Writing a fine grained kernel is hard, especially when you need to support some functionality that's not so friendly for large MP systems.
Maybe Dillon's approach is right. Instead of trying to coordinate actions between processors in a lock free or finely grained manner while trying to maintain tons of shared state, why not treat your large MP machine as many smaller ones that are coordinated at a higher level?
This is the McVoy cache coherent cluster approach
http://www.bitmover.com/cc-pitch/
It has always seemed like hadwaving to me. The problem with this is: "what higher level?"
What does it buy you to program a multiprocessor system as a set of communicating cluster nodes, that you can't do as a monolithic kernel? As far as I can see, it only serves to place restrictions on the ways you can communicate and interact between CPUs.
So why do proponents of this approach think they can just assert that a system of communicating nodes -- that *must* still be synchronized and share data at some points -- can scale as well as a monolithic kernel? I don't think that is a given at all.
The Google cluster is a great example of this. They don't really need a scalable OS at all: a simple kernel that efficiently manages I/O and gets out of the way of the one executing task on a particular node is all that's needed.
Well, they use Linux, and actually they are pushing some pretty complex functionality into the kernel (to do resource control, for example).
Everything else is coordinated from their aggregation servers and their distributed namespace/locking system.
And I don't know what it's requirements are, but you can bet it's nothing like a regular UNIX filesystem / POSIX API.
Also, I don't see why you think Google is a great example of this. Google does not have a large MP machine. It has a big, non-cache-coherent cluster. So there is only one way to program it -- like a cluster.
News
Linked by Thom Holwerda on 06/18/13 22:33 UTC
Official Apple statement on PRISM and privacy: "Regardless of the circumstances, our Legal team conducts an evaluation of each request and, only if appropriate, we retrieve and deliver the narrowest possible set of information to the authorities. In fact, from time to time when we see inconsistencies or inaccuracies in a request, we will refuse to fulfill it." This is basically Apple re-publishing their earlier statement in a more official manner. You either believe it, or you don't.
Linked by Anonymous on 06/18/13 22:26 UTC
The open source Contiki operating system and its commercial Thingsquare distribution are making strides towards the connected home. According to a Computerworld article, a new LED light bulb manufacturer is putting small computers into their light bulbs. Each computer runs the Contiki OS, which gives each bulb an IP address and allows them to be controlled with a smartphone application. To connect the bulbs to the application, the bulbs use both Wi-Fi and the much lower power IEEE 802.15.4 mesh technology.
Linked by Thom Holwerda on 06/18/13 22:25 UTC
"Google asked the secretive Foreign Intelligence Surveillance Court on Tuesday to ease long-standing gag orders over data requests it makes, arguing that the company has a constitutional right to speak about information it's forced to give the government. The legal filing, which cites the First Amendment's guarantee of free speech, is the latest move by the California-based tech giant to protect its reputation in the aftermath of news reports about sweeping National Security Agency surveillance of Internet traffic." Draining the ditch after the cow has drowned in it.
Linked by Thom Holwerda on 06/18/13 17:45 UTC
"I can't find one person who has been using the Nexus 7 for an extended period of time, and hasn't seen a massive downgrade in performance. Just what kind of downgrade are we talking here? I cannot pick up my Nexus 7 without experiencing problems like a lag of ten seconds, or more, just to rotate the display; touches refusing to acknowledged; stuttering notification panel actions; and unresponsive apps." Fully and utterly agreed. My Nexus 7 was blazing-fast and awesome for a few months, and at some point, it just started sucking. Just like that. I've tried loads of ROMs, and nothing helps.
Linked by Thom Holwerda on 06/18/13 17:32 UTC, submitted by poundsmack
A new release of the hobby operating system MenuetOS! The release notes are a bit non-descript, but you'll have to take what you can get: "updates and improvements (picview, httpc, ehci, ...)".
Linked by Thom Holwerda on 06/17/13 17:58 UTC
"The Internet is one of the most transformative technologies of our lifetimes. But for 2 out of every 3 people on earth, a fast, affordable Internet connection is still out of reach. And this is far from being a solved problem. There are many terrestrial challenges to Internet connectivity - jungles, archipelagos, mountains. There are also major cost challenges. Right now, for example, in most of the countries in the southern hemisphere, the cost of an Internet connection is more than a month's income. Solving these problems isn't simply a question of time: it requires looking at the problem of access from new angles. So today we're unveiling our latest moonshot from Google[x]: balloon-powered Internet access." Insane.
Linked by Thom Holwerda on 06/17/13 17:52 UTC
"MineAssemble is a tiny bootable Minecraft clone written partly in x86 assembly. I made it first and foremost because a university assignment required me to implement a game in assembly for a computer systems course. Because I had never implemented anything more complex than a 'Hello World' bootloader before, I decided I wanted to learn about writing my own kernel code at the same time. Note that the goal of this project was not to write highly efficient hand-optimized assembly code, but rather to have fun and write code that balances readability and speed. This is primarily accomplished by proper commenting and consistent code structuring." Just cool.
Linked by Thom Holwerda on 06/14/13 21:03 UTC
Jon Rubinstein, former CEO of Palm: "Well, I'm not sure I would have sold the company to HP. That's for sure. Talk about a waste. Not that I had any choice because when you sell a company you don't get to decide that. Obviously, the board and shareholders decide that. If we had known they were just going to shut it down and never really give it a chance to flourish, what would have been the point of selling the company? I think the deal we had with Verizon really hurt us, but who knew that at the time? These things are all hindsight."
Linked by Thom Holwerda on 06/14/13 20:46 UTC
"And so it is with Dell's Alienware X51 R2, a small form factor gaming PC in console digs. It's shaped similar to Microsoft's Xbox 360 Slim, and though it's slightly larger than either a 360 or PlayStation 3, the X51 R2 would be right at home in a living room setting nestled next to a large screen TV. Indeed, it's adept at running Steam's Big Picture mode, and if your primary objective is to play games in the living room, go ahead and consider the X51 R2 a hybrid game console." This is obviously not the only machine like this - still, these are very valid console alternatives even for those that don't like being hunched over with a cramped WASD-claw. Also, PC gamers among us: could you get away with the $699 model for gaming?
Linked by Thom Holwerda on 06/14/13 17:32 UTC
From Bloomberg: "Microsoft, the world's largest software company, provides intelligence agencies with information about bugs in its popular software before it publicly releases a fix, according to two people familiar with the process. That information can be used to protect government computers and to access the computers of terrorists or military foes." The lid has officially been blown off.More News »
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Member since:
2005-07-21
It's a shame that one cannot moderate after having posted, for I would have moderated you up for such a well-written, informative post.